According to New Testament History by F.F.Bruce, reading from his chapter on Judaea under Roman governors, Pilate had engaged in oppressive acts against the Jews, and finally ran into trouble when he sent some infantry and cavalry to deal with some Samaritans who had gathered to hear an announcement by someone claiming to be a prophet on Mount Gerizim. Perhaps this would-be prophet was claiming to be the prophet like Moses mentioned in Deuteronomy 18. There was a lot of bloodshed and the Samaritans complained to the Legate of Syria, Lucius Vitellius (AD 35-39), and Vitellius ordered Pilate in 36 AD to return to Rome to give an account to the Emperor. Tiberius died in March 37 AD and the new Emperor did not reappoint Pilate.

The Gerizim atrocity reference is taken from Josephus Antiquities xviii.

The edition of New Testament History I refer to is dated 1971 (revised edition) so not a recent book on this time, and F.F.Bruce was then Rylands Professor of Biblical Criticism and Exegesis at the University of Manchester, so probably an out-and-out historian would be a preferable source (He was also someone of evangelical christian faith.)